Oh, and that new president to say "Hey" to, looking sleek in a black tux, even if that white tie was cocked a bit off-center.

In Mr. Obama's neighborhood last night, Mary J. Blige couldn't stop the tears up onstage. Stevie Wonder was on the keyboard. And when the new president mixed with the crowd, ABC -- the only people with live cameras in the room -- cut to commercial.

Even with those blind spots, it was a glittering start to a 10-ball night, a night when it didn't seem to matter that the temperature was less than 28 degrees and the wind was cutting through the thickest overcoats. A night when it began to sink in that the once unthinkable had happened in America.

Obama launched it with the Neighborhood Ball at the Walter E. Washington Convention Center, which hosted six of the balls and teemed with tens of thousands of smiling, cheering, utterly exuberant partygoers. The new president and first lady shared the stage for their first dance with Beyoncé, who serenaded them. Obama, confronted with one of the entertainment world's hottest babes, wisely kept his eyes on the new first lady, Michelle Obama.

"First of all, how good-looking is my wife?" Obama said, beaming. (He wasn't the only one feeling frisky. Later, at Vice President Biden's Home States Ball, he gazed approvingly at his wife, Jill. "I may not be able to dance," he said, "but I sure like holding her.")

People in the audience liked what they were seeing, too. At the Neighborhood Ball, Carly Dodson, a student from Springfield, screamed, "Look how hot Michelle's looking with that one-shoulder dress."

The Obamas, who displayed a kind of electric chemistry during the campaign, danced with cheeks touching as Beyoncé purred the Etta James classic "At Last." Michelle rubbed his back; he drew "oohs" from the audience by giving her a twirl, then tapped his left foot somewhat awkwardly to keep time.

But they really got going once the first dance was out of the way. Wonder led a gaggle of celebs -- Shakira, Faith Hill and Mariah Carey among them -- in singing "Signed, Sealed, Delivered," and a group of people who took the train down to Washington with Obama spilled onstage to shake it with him. Obama delivered a rare presidential hip bump to one of the ballgoers. This from the man who wrote that when he was in school, he reasoned, "I couldn't croon like Marvin Gaye, but I could learn to dance all the 'Soul Train' steps."

Afterward, Jamie Foxx declared approvingly: "You can tell that's a black president by the way he was moving."